Question about adding a comma

0

Where would I need to add commas in this sentence? Or would it need a semi colon?

See example:

Within the broad canon that is classical music, few composers meant more to Nathaniel Ayers than Ludwig van Beethoven whose pieces not only afforded Ayers a rare and essential source of stability, but provided an effective medium of communication between the mentally ill artist and the Los Angeles Times journalist who would eventually take up his cause, Steve Lopez.